And can I say how happy I am that the fists seem to be additional parts instead of stupid integrated not-hands like they tried to do with Fall of Cybertron Bruticus?

Photos where you can see the side of a gestalt leg show that the foot pieces have heel supports that look just like the thumbs. All the gestalt toes look like pairs of cannons. It looks like they went the Energon combiner route and had the feet/hands change into weapons for the limb-bots. From the close-ups, they used the same basic design for all the hand-feet, but with different sculpting detail. This should work particularly well for the Stunticons, since they each came with a double barreled cannon for their car mode.

This also explains why the hands are big, since they have to transform into feet that can support the whole bot. It looks like the cannons aren't the fingers, so maybe the actual hand part of the hand is somewhat proportionate, but the extra mass of the same-colored cannons make them look bigger.